The Lucas series or Lucas numbers are an integer sequence. Fibonacci numbers and Lucas numbers form complementary instances of Lucas sequences.
The sequence of Lucas numbers is: 2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123,.....
Ln = 2 if n = 0;
Ln = 1 if n = 1;
Ln = Ln-1 + Ln-2 if n ＞ 1;